The invention relates to a method and a device for determining angular velocity from two voltage signals produced by an angle transmitter which signals have a sinusoidal course with respect to the angle of rotation of a rotatable body and are shifted 90 degrees in phase with respect to each other.
For relatively slow linear or rotating movements, detection of the instantaneous speed is difficult and expensive. In speed-of-rotation transmission systems or in angle decoders, high resolutions are necessary for the continuous determination of the angular velocity inasmuch as disturbing sudden changes occur in the values of the angular velocity as a result of sequential discrete speed-of-rotation data. With two small a number of pulses per revolution it is necessary therefore to form a mean value which results in a lag time and can frequently not be used in true-time applications.
With an angle transmitter (for instance, resolver, potentiometer, magnet field sensor, etc.) the instantaneous position angle can be detected. One widely used form of signal is the sine-cosine system by which the angle of rotation of a rotating member can be unambiguously defined with respect to a zero position. Every change in angle causes a corresponding change in signal of the sine and cosine measurement channels.
It is an object of the present invention to provide a method of determining the angular velocity from two voltage signals produced by an angle transmitter which have a sinusoidal course with respect to the angle of rotation of a rotatable member and are shifted by 90 degrees in phase with respect to each other, and to develop a circuit for the carrying out of the method.